The invention relates to a method for stacking containers formed of a thermoplastic plastic, which containers are molded and punched out of a film strip, are transferred out of the molding tool in stacking magazines, are removed as stacks from the magazines, and then are further processed. The invention further relates to an apparatus for executing the method.
In known apparatuses (xc3x9cG models of the Assignee, ADOLF ILLIG Maschinebau GmbH and Co.), the containers are ejected from the molding tool, which is pivoted by about 80xc2x0 from the work position, directly into stacking troughs that extend flush with the transfer position in the axial direction. In another known apparatus of the Assignee, described in German Patent Document DE 198 52 359 A1, it is known to pivot the containers by 180xc2x0 before stacking them in the stacking magazines so that they can be inserted bottom or floor-first into the containers that are already stacked.
In the two known embodiments, a plurality of stacking magazines forms a stacking-magazine row, and a plurality of stacking-magazine rows forms a complete stack cagexe2x80x94corresponding to the number of pieces molded in the molding tool. From the stack cage, all of the formed container stacks can be simultaneously removed with an ejection rake or tool and transferred into a receiving chamber in a known manner. However, it may be necessary to displace the entire stack cage in the stacking direction between two cycles to bring the ejector rake into the ejection position. With a large number of cycles and pieces, which results in a large and heavy stack cage, the process of displacing the entire stack cage, pivoting the ejection rake and returning the stack cage into the stacking position between two cycles causes time-related problems, and limits the number of cycles for the apparatus. The necessary rapid clearing of the stack cage causes the container stacks to be compressed, which impedes the separation of the containers, e.g., in filling machines and beverage machines, thereby leading to operating disturbances or problems. The rapid displacement of the stack cage requires high inertial forces, and correspondingly large drives with precise holding points, for guiding the stack cage precisely into its end position. These drives are costly.
If the containers that are ejected in stacks from the stacking magazines are to be further processed, e.g., through bordering, imprinting, or column-wise packaging in cartons, first it is necessary to transfer all of the container stacks consecutively into a row. In the known apparatuses, after all of the container stacks have been cleared, they are transferred into a format-dependent receiving chamber, in which pushing elements transfer the individual container stacks in rows onto a transversely-extending conveyor belt that cyclically transfers the individual container stacks onto a conveyor belt that runs in the stacking direction. This transfer process is susceptible to disturbances due to the drifting apart of the container stacks, depending on the container shape (amount of tapering, diameter, height). The receiving chamber is format-dependent, and must either be exchanged as a whole when the apparatus is converted, or changed over to a new container format, which is a complicated process that requires the chamber to be adjustable.
It is the object of the invention to provide a method that permits a high cycle number for the apparatus, without receiving a fast and position-precise displacement of the entire stack cage between two cycles of the upstream molding machine. The method is further intended to reduce the susceptibility of the apparatus to disturbances, as dictated by the handling of the individual container stacks. The method is intended to require simple format parts, and permit a rapid format change when the apparatus is changed over to a different container format. There should be no need for a receiving chamber for receiving all of the ejected container stacks before they are brought together one behind the other.
The above object generally is achieved according to a first aspect of the present invention by a method for stacking containers formed of thermoplastic plastic, which containers are molded and punched out of a film strip, are transferred out of the molding tool in stacking magazines, are removed as stacks from the magazines, and are then further processed, which method comprises: providing a plurality stacking-magazine rows comprised of individual, connected stacking magazines, with the number of stacking-magazine rows outnumbering the number of container rows in the molding tool of the upstream molding machine by at least one; removing containers from the molding tool and stacking the containers in the stacking magazines located in the stacking station; displacing all of the stacking-magazine rows located in the stacking station together, in a direction perpendicular to the stacking direction, by the distance between two stacking-magazine rows; transferring the front stacking-magazine row, in the direction of displacement, to a stack-removal station located to the side of the stacking station; emptying the stacking-magazine row located in the stack-removal station; and, transferring the stacking-magazine row located in the stack-removal station onto the stacking-magazine row located in the rear, seen in the displacement direction, in the stacking station.
The above object generally is achieved according to a second aspect of the invention by an apparatus for stacking containers, formed of thermoplastic plastic, downstream of a molding machine, comprising: a plurality of stacking-magazine rows formed of connected individual stacking magazines in which the containers are stacked; a stacking station in which the stacking-magazine rows are set one on top of the other to form a stack cage, can be separated from one another, and can be displaced perpendicular to the stacking direction for containers received by the magazines; a displacement device for transferring the respective lowermost stacking-magazine row from the stacking station into a stack-removal station disposed to the side of the stacking station, the device having a displaceable rake for simultaneously guiding container stacks out of the stacking containers of a row; and a transfer device for transferring the emptied stacking-magazine rows from the stack-removal station onto the rear stacking-magazine row, seen in the direction of displacement of the stacking-magazine rows, in the stacking station. Advantageous modifications of the invention are discussed. The method is described in detail in conjunction with the schematic drawings of the apparatus.